JP3504405B2 - Diesel engine oil composition - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to diesel engine oil compositions. Specifically, it relates to a so-called low phosphorus low ash type diesel engine oil composition having a low phosphorus component and a low sulfated ash content.

Since the call for environmental protection has been increasing, regulations on automobile exhaust gas have become increasingly stringent in countries around the world.
There is a further demand for reduction of Ox and PM (particulate matter). Techniques for reducing NOx and PM in exhaust gas include engine modification (delaying fuel injection timing, increasing fuel injection pressure, improving combustion chamber shape, etc.), EGR
In addition to (exhaust gas recirculation), post-treatment technology for exhaust gas is being studied. Then, SOF (organic solvent-soluble) oxidation catalyst and diesel particulate filter (DPF)
Is a typical example of post-processing technology. In terms of the effect of the lubricating oil (engine oil) used in the diesel engine on the above-mentioned post-treatment technology, the durability (life) of the SOF oxidation catalyst is that the engine oil is high phosphorus high ash type (usually Diesel engine manufacturers say that even if it is engine oil containing 0.1 to 0.13 mass% of phosphorus concentration and 1.4 to 2 mass% of sulphate ash), there is no particular problem. Has been reported by. Therefore, as a matter of course, the low phosphorus low ash type engine oil does not adversely affect the durability (lifetime) of the SOF oxidation catalyst, and rather, rather than the case of using the high phosphorus high ash type engine oil. The life can be extended. On the other hand, DPF
Is that the ash accumulation in the DPF increases in proportion to the sulfated ash content of the engine oil, and the pressure loss increases accordingly. Therefore, the diesel engine engine oil equipped with the DPF is a low phosphorus low ash type. There must be. Low phosphorus and low ash in engine oils contributes to the anti-wear and anti-oxidant properties of lubricating oils by zinc dialkyldithiophosphate (ZDTP) and the metal-based detergents that contribute to the detergency and acid-neutralizing properties of lubricating oils. It is possible to reduce the compounding amount. However, simply doing so would necessarily reduce the performance of the engine oil. Therefore, while being low phosphorus low ash type, wear resistance,
The development of diesel engine oils that are excellent in cleanliness, oxidation stability, base number maintenance, etc. is highly anticipated in the industry.

[0003]

INDUSTRIAL APPLICABILITY The present invention can be applied to a diesel engine equipped with a DPF and exhibits excellent effects such as anti-wear property, cleanability, oxidation stability and base number maintenance property. It provides a low phosphorus low ash type engine oil.

[0004]

Means for Solving the Problems As a result of intensive studies aimed at solving the above-mentioned problems, the present inventors have found that by adding a specific amount of a lubricating oil additive as described below to a base oil, It was found that the desired diesel engine oil was obtained. That is, 0 one diesel engine oil provided by the present invention (hereinafter referred to as engine oil A) is a mineral oil and / or synthetic oil as a base oil, (1) a zinc dialkyldithiophosphate in Li emissions equivalent concentration 0.04 to 0.08% by mass, (2) total base number of 150 to 200 mgKOH / g
Calcium carbonate overbased calcium salicylate and / or total base number of 150-250 mg KOH /
g of calcium borate overbased calcium salicylate in terms of calcium concentration of 0.07 to 0.22% by mass, and (3) number average molecular weight of 2000 to 5000.
In a bis type boric acid-modified succinimide ashless dispersant containing respectively 0.04 to 0.08% by weight boric oxygen concentration terms, and in the amount of sulfated ash content 0.4-0.8 wt% It is characterized by being. In addition, another one of the diesel engine oils according to the present invention (hereinafter, referred to as Engine Oil B
Is based on mineral oil and / or synthetic oil,
(1) 0.04-0.08 wt% of zinc dialkyldithiophosphate in Li emissions equivalent concentration, (2) a total base number 150
200 mg KOH / g calcium carbonate overbased calcium salicylate and / or total base number of 150
0 calcium borate overbased calcium salicylate is ~250mgKOH / g at a calcium concentration conversion.
05-0.2 mass%, and (3) total base number of 50-
100 mg KOH / g basic calcium phenate and / or total base number 10-50 mg KOH / g
E 0.01-0.02 mass% of basic calcium sulfonate with calcium equivalent concentration, as well as (4) a number average molecular weight of bis type imide boric acid-modified succinic ashless dispersant is a 2000 to 5000 is It is characterized by containing 0.04 to 0.08 mass% in terms of arsenic concentration and having a sulfated ash content of 0.4 to 0.8 mass%.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION As the base oil for each of the engine oils A and B of the present invention, both mineral oils and synthetic oils can be used. Mineral oils or synthetic oils, or mineral oils and synthetic oils can be used. It is also possible to mix with and in any proportion to be used as a base oil. Mineral oil-based base oil, the lubricating oil fraction obtained by atmospheric distillation and vacuum distillation of crude oil, solvent desorption,
A product obtained by performing one or more optional treatments such as solvent extraction, hydrocracking, solvent dewaxing and hydrorefining is usually used. The synthetic base oil may be aromatic or non-aromatic. Examples of the aromatic synthetic base oil include alkylnaphthalene and alkylbenzene. Examples of the non-aromatic base oil include poly-α-exemplified by 1-octene oligomer, 1-decene oligomer and the like.
Olefin and hydrides thereof; diesters such as ditridodecyl glutarate, di2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di3-ethylhexyl sebacate; trimethylolpropane cabrylate, trimethylolpropane pelargonate, pentaerythritol 2 Examples thereof include polyol esters such as ethylhexanoate and pentaerythritol pelargonate. The viscosity of the base oil can be arbitrarily selected according to the viscosity setting of the mono-grade oil or the multi-grade oil, but is usually 100 ° C.
It is preferable that the kinematic viscosity at ² to 50 mm ² / s.

In the engine oils A and B of the present invention,
One of the essential components of each is zinc dialkyldithiophosphate represented by the following general formula.

[Chemical 1] In the above formula, R ¹ , R ² , R ³ and R ⁴ each have 2 carbon atoms.
~ 18, preferably 3-8, alkyl groups, preferably primary or secondary alkyl groups, which may be linear or branched. Specific examples of the above alkyl group include linear or branched, primary or secondary alkyl groups.
Grade ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, Examples include octadecyl group. In each of the engine oils A and B of the present invention, the content of zinc dialkyldithiophosphate has a lower limit of 0.
It is 04% by mass, preferably 0.05% by mass, and the upper limit is 0.08% by mass, preferably 0.07% by mass. When the content of the component in the engine oils A and B is less than the above lower limit value of 0.04 mass%, the valve operating system wear resistance of the obtained engine oil is deteriorated, and the upper limit value of 0. If the amount exceeds 08% by mass, the sulfated ash content of the engine oil increases, which is not preferable.

Another one of the essential components of the present invention is a calcium component. The calcium component in engine oil A is calcium carbonate overbased calcium salicylate and / or calcium borate overbased calcium salicylate (hereinafter referred to as calcium component (a)).
And the calcium component of the engine oil B is both the above-mentioned calcium component (a) and basic calcium phenate and / or basic calcium sulfonate (hereinafter referred to as calcium component (b)). . As the calcium carbonate overbased calcium salicylate, the lower limit of the total base number is 150 mgKOH / g, preferably 160 mgKOH / g, and the upper limit is 200 m.
gKOH / g, preferably 180 mgKOH / g, is used. As calcium borate overbased calcium salicylate, the lower limit of the total base number is 150 mgKO.
H / g, preferably 180 mgKOH / g, with an upper limit of 250 mgKOH / g, preferably 200 mgKOH
/ G is used. Further, as the basic calcium phenate, the lower limit of the total base number is 50 mgKOH /
g, preferably 60 mgKOH / g, with an upper limit of 10
0 mgKOH / g, preferably 80 mgKOH / g is used, and as the basic calcium sulfonate, the lower limit of the total base number is 10 mgKOH / g, preferably 15 mgKOH / g, and the upper limit is 50 mgKOH / g.
g, preferably 30 mg KOH / g is used. By the way, if the total base number of the basic calcium phenate exceeds 100 mgKOH / g, the detergency of the ringland deteriorates, and if the total base number of the basic calcium sulfonate exceeds 50 mgKOH / g, the cleaning around the piston becomes Conversion performance decreases. The total base number as to the calcium component used in the present invention refers to JIS K 2501.
It means a value measured in accordance with "Petroleum products and lubricants-Neutralization number test method (perchloric acid method)" of (1992).

Calcium component (a) used in the present invention
May be produced by any method as long as it satisfies the total base number defined above. Therefore, they can be manufactured by any method. For example, calcium carbonate overbased calcium salicylate can be obtained by overbasing neutral calcium salicylate with calcium carbonate, and calcium borate overbased calcium salicylate is neutralized with calcium borate. It can be obtained by basification. Here, the neutral calcium salicylate refers to a salt obtained by neutralizing a hydrocarbon group-substituted salicylic acid with an equivalent amount of calcium hydroxide or calcium oxide, and the neutral salt can be generally represented by the following general formula.

[Chemical 2] In the above formula, R ⁵ has 12 to 30 carbon atoms, preferably 14 to 1 carbon atoms.
8 represents a hydrocarbon group such as an alkyl group, an alkenyl group, an aryl group, an alkylaryl group, and an arylalkyl group, and an alkyl group is particularly preferable. Specific examples of the alkyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group,
Examples thereof include a henicosyl group, a docosyl group, a tricosyl group, a tetracosyl group, a pentacosyl group, a hexacosyl group, a heptacosyl group, an octacosyl group, a nonacosyl group, and a triacontyl group (all including all structural isomers). The neutral calcium salicylate has 14 carbon atoms.
After alkylating the phenol with a mixture of α-olefins of -18, introduce a carboxyl group by Kolbe reaction,
Those neutralized with calcium are preferably used.

In the calcium component (b) used in the present invention, specific examples of the basic calcium phenate include straight chain or branched chain alkyl groups having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms. Examples thereof include alkylphenols, alkylphenol sulfides, and Mannich reaction products of alkylphenols, which are treated with calcium hydroxide or oxide. Also,
In the present invention, the basic calcium sulfonate that can be used as the calcium component (b) has a molecular weight of 300 to
1,500, preferably 400 to 700 alkylaromatic compounds, for example, alkylaromatic sulfonic acid obtained by sulfonating with fuming sulfuric acid or sulfuric anhydride, treated with calcium hydroxide or oxide. It can be illustrated. Alkyl aromatic sulfonic acids include so-called petroleum sulfonic acids and synthetic sulfonic acids. In addition, petroleum sulfonic acids include those obtained by sulfonating an alkyl aromatic compound generally contained in a lubricating oil fraction of mineral oil, and mahogany acid produced as a by-product during the production of white oil.Synthetic sulfonic acids include an alkylbenzene production plant. Sulfonated product of alkylbenzene having a linear or branched alkyl group, which is by-produced from, sulfonated product of alkylbenzene having a linear or branched alkyl group obtained by alkylating benzene with a polyolefin, Is a sulfonated product of alkylnaphthalene exemplified by dinonylnaphthalene.

As for the content of the calcium component in the engine oil, the engine oil A of the present invention has a calcium component (a) of 0.07% by mass in terms of calcium concentration.
Or more, preferably 0.10 mass% or more, and the upper limit is 0.22 mass%, preferably 0.17 mass%. In the engine oil A, when the content of the calcium component (a) is less than 0.07% by mass in terms of calcium concentration, the acid neutralization property of the engine oil is insufficient, so that the engine oil is deteriorated. It easily occurs and the engine cleanliness is insufficient. Further, when the content of the calcium component (a) exceeds 0.22 mass% in terms of calcium concentration, the amount of sulfated ash in the engine oil increases, which is not desirable.
The engine oil B of the present invention contains the calcium component (a) in an amount of 0.05% by mass or more, preferably 0.1% by mass or more in terms of calcium concentration, and the upper limit value is 0.2% by mass,
It is preferably 0.15% by mass. The engine oil B also contains 0.01 to 0.02% by mass of the calcium component (b).
It is contained in the range of. In the engine oil B, the content of the calcium component (a) is 0.05 in terms of calcium concentration.
If the amount is less than mass%, the acid neutralization property of the engine oil is insufficient, so engine oil is likely to deteriorate,
Engine cleanliness is insufficient. On the other hand, the content of the calcium component (a) is 0.2% by mass in terms of calcium concentration.
If it exceeds, the amount of sulfated ash in the engine oil increases, which is not desirable. Further, in the engine oil B, when the content of the calcium component (b) is less than 0.01% by mass in terms of calcium concentration, the engine oil B cannot be provided with sufficient piston cleanliness. Then, setting the content of the calcium component (b) to 0.02 mass% or more in terms of calcium concentration means that the engine oil B
Not recommended because it causes an increase in sulfated ash content.

In the engine oils A and B of the present invention, the other essential component is a boric acid-modified succinimide ashless dispersant (hereinafter referred to as a dispersant component). As the dispersant component, those having a number average molecular weight in the range of 2000 to 5000 can be used, but the lower limit of the number average molecular weight is preferably 2300, and the upper limit thereof is preferably 35.
00. When the number average molecular weight of the dispersant component is less than 2000 or exceeds 5000, the contact surfaces of the camshaft and the valve lifter may be damaged. Examples of the dispersant component that can be used in the present invention include those obtained by modifying the monoimide represented by the following general formula (1) and / or the bisimide represented by the general formula (2) with boric acid.

[Chemical 3]

[Chemical 4] In the general formulas (1) and (2), R ⁶ , R ⁷ and R
Each ⁸ independently represents a polybutenyl group having a number average molecular weight of 900 to 2000, and n is 2 to 5, preferably 4 to 5
Indicates the number of. The above monoimide and bisimide are, for example, polybutene having a number average molecular weight of 900 to 2000 or chlorinated polybutene, and maleic anhydride and 100 to 20.
It can be obtained by reacting at 0 ° C. and reacting the obtained polybutenyl succinic acid with a polyamine. As the polyamine in this case, for example, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and the like can be used. The engine oils A and B of the present invention each contain a dispersant component in an amount of 0.04% by mass or more, preferably 0.05% by mass or more in terms of boron concentration, but the upper limit is 0 in terms of boron concentration. 0.08% by mass, preferably 0.06
It is% by mass. When the content of the dispersant component calculated as the boron concentration is less than 0.04% by mass, not only the base number of the engine oil is insufficient, but also the cleanliness and antiwear properties are insufficient, resulting in 0.08%. When the content exceeds the mass%, the low temperature viscosity of the engine oil increases, which is not desirable.

The lower limits of the amounts of sulfated ash in the engine oils A and B of the present invention are 0.4% by mass, preferably 0.6% by mass, and the upper limits thereof are 0.8% by mass, preferably 0. It is 75% by mass. Sulfated ash content is 0.4% by mass
If the amount is less than 1.0%, both the engine oils A and B are deteriorated in wear resistance, cleanliness, and base number retention, and if it exceeds 0.8% by mass, the low ash reduction intended by the present invention cannot be realized. . The sulfated ash content in the present invention refers to JIS K 2
272 (1985) “Ash content of crude oil and petroleum products and sulfate ash content test method”, that is, sulfuric acid ash content, that is, sulfuric acid is added to a carbonization residue produced by burning a sample and heated to a constant weight. means.

As long as the object of the present invention is not impaired, the engine oil composition of the present invention may be variously used in lubricating oil compositions in addition to the above-mentioned viscosity index improver and pour point depressant. Additives can be added. The preferred specific examples of the additives that can be blended are as follows. Phenol-based ashless antioxidant : 4,4'-methylenebis (2,6-di-tert-butylphenol), 4,4'-
Bis (2,6-di-tert-butylphenol), 4,4
′ -Bis (2-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert)
-Butylphenol), 4,4'-butylidene bis (3
-Methyl-6-tert-butylphenol), 2,2'-
Methylenebis (4-methyl-6-nonylphenol),
2,2'-isobutylidene bis (4,6-dimethylphenol), 2,2'-methylenebis (4-methyl-6-)
Cyclohexylphenol), 2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6-te
rt-butylphenol), 2,6-di-tert-α-dimethylamino-p-cresol, 2,6-di-tert-butyl-4 (N, N′-dimethylaminophenol), 4,
4'-thiobis (2-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-
Butylphenol), 2,2'-thiobis (4-methyl-6-tert-butylphenol), bis (3-methyl-)
4-hydroxy-5-tert-butylbenzyl) sulfide, bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, 2,2'-thio-diethylenebis [3- (3,5-di) -Tert-butyl-4-hydroxyphenyl) propionate], tridecyl-3- (3,3
5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis [3-
(3,5-Di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-
Di-tert-butyl-4-hydroxyphenyl) propionate, etc., amine-based ashless antioxidant : phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, dialkyldiphenylamine, etc., rust inhibitor : alkenyl succinate, polyvalent such as alcohol esters, demulsifiers: polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyalkylene glycols such as polyoxyethylene alkyl naphthyl ether-based non-ionic surfactants, defoamers: silicones, fluorosilicones, fluoroalkyl ethers such as, metal deactivators imidazolines, pyrimidine derivatives, alkyl thiazole, mercaptobenzothiazole, benzotriazole or derivatives thereof, 1,3,4-thiadiazole polysulfide Fido, 1,3,4-thiadiazole-2,5-bis dialkyl dithiocarbamate, 2-
(Alkyldithio) -benzimidazole, β- (o-
Friction modifiers such as carboxybenzylthio) propionnitrile: molybdenum dithiophosphate, molybdenum dithiocarbamate, long chain fatty amines, long chain fatty acids, long chain fatty acid esters, long chain fatty alcohols, etc.

The engine oil composition of the present invention (collectively the above engine oils A and B; the same applies hereinafter) can be used as a monograde oil or as a multigrade oil. In the case of preparing a multigrade oil, for example, 10W-30 oil, a mineral oil and / or a synthetic oil having a kinematic viscosity at 100 ° C. of 3.8 to 6.5 mm ² / s is selected as a base oil, and the above-mentioned oil is used. Each of the above essential components of the present invention is added, and a viscosity index improver and a pour point depressant are further added to give a composition having a kinematic viscosity at 100 ° C. of 9.3 to 1.
By adjusting to 2.5 mm ² / s, the target multigrade oil can be obtained. In this case, as the viscosity index improver, polymethacrylate, an olefin copolymer or a hydride thereof, a graft copolymer or a hydride thereof obtained by grafting a methacrylate onto an olefin copolymer, a mixture of a polymethacrylate and an olefin copolymer or a hydride thereof, and the like are used. it can. The above-mentioned olefin copolymer is, for example, a copolymer of ethylene and an α-olefin having 3 to 18 carbon atoms. The weight average molecular weight of the above polymethacrylate is usually in the range of 50,000 to 1,000,000, and the olefin copolymer or its hydride has the same weight average molecular weight of 10,000 to 500,000.
It is in the range of 0. In addition, the above graft copolymer,
Similarly, the weight average molecular weight is 50,000 to 1,000,0.
It is in the range of 00. In addition, polymethacrylate also exhibits the effect as a pour point depressant. The blending amounts of the viscosity index improver and the pour point depressant are selected according to the desired viscosity grade, but are generally in the range of 0.1 to 20 mass% based on the total amount of the engine oil composition. . In the engine oil composition of the present invention, the lower limit of the amount of sulfated ash is 0.4% by mass, preferably 0.6% by mass, and the upper limit is 0.8% by mass, preferably 0.75% by mass. is important. If the sulfated ash content of the composition is less than 0.4% by mass, problems with practical performance such as deterioration of antiwear property or cleaning property and deterioration of base number retention property are unfavorable. Also,
If the sulfated ash content of the composition exceeds 0.8 mass, it is not preferable because the meaning of lowering the ash is weakened, the accumulation of zinc and calcium in the DPF is accelerated, and the exhaust gas is adversely affected. Therefore, even if one or more of the above additives are added as necessary, it is important that the amount of sulfated ash of the engine oil composition after addition is maintained within the above range. . When adding the above-mentioned additives to the engine oil composition of the present invention, the sulfated ash content of the engine oil composition after addition is taken into consideration, and the total amount of the composition is 0.2% for the ashless antioxidant. ˜2% by mass, 0.2 to 1% by mass for rust inhibitor, 0.05 to 1% by mass for demulsifier, 0.0005 to 1% by mass for defoamer, and about metal deactivator. The addition amount of each additive is selected in the range of 0.005 to 1% by mass and the friction modifier in the range of 0.1 to 2% by mass.

[0015]

EXAMPLES The contents of the present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Each engine oil composition having the composition shown in Table 1 and Table 2 was prepared, and these performance evaluation tests were conducted by the following method. The test results are shown in Tables 1 and 2.

[Table 1]

[Table 2] (Engine oil performance evaluation test) The sample oil was evaluated by JASO (Ja
panese Automobile Standard Organization) Cleanliness test (JASO M 336-90). The engine used is an in-line 4-cylinder engine, displacement 2.2 dm ³ , OHV type. Operating conditions are oil temperature 120 ° C and rotation speed 4000
The test time was 100 hours with rpm and full load. And for the fuel, considering future emission regulations,
A sulfur content of 0.04 mass% was used. The composition of the base oil used when preparing each engine oil composition and the details of the additives added to the base oil are shown below. Base oil composition Mineral oil-1: Mixture of hydrocracked oil (85 mass%) and solvent refined mineral oil (15 mass%), 100 ° C kinematic viscosity 5.23 mm
² / g, viscosity index 127, mineral oil-2: solvent refined mineral oil, 100 ° C. kinematic viscosity 4.82 mm
² / g, viscosity index 104 Mineral oil-3: Solvent refined mineral oil, 100 ° C. kinematic viscosity 8.49 mm
² / g, viscosity index 97 Synthetic oil-1: Mixture of poly-α-olefin (80 mass%) and ester of trimethylolpropane (20 mass%), 100 ° C kinematic viscosity 9.99 mm ² / g, viscosity index 14
1 additive Ca salicylate-1: calcium carbonate overbased calcium alkyl salicylate (having 14 to 14 carbon atoms in the alkyl group)
18) Ca salicylate-2: calcium borate overbased calcium alkyl salicylate (having 14 carbon atoms in the alkyl group)
~ 18) Ca phenate: basic calcium salt Ca sul phosphonates of Mannich reaction product of alkylphenol having 12 carbon atoms: alkyl sulfates e ne <br/> over preparative basic calcium salt ashless dispersants 9-18 carbon atoms - 1: the number which the polybutenyl group-containing bis-imide of succinic acid and tetraethylene pentamine having an average molecular weight of 1300 was modified with boric acid (Mn = 3000) ashless dispersants -2: polybutenyl group-containing succinic acid number average molecular weight 1300 and tetraethylene pentamine Bisimide (Mn
= 2400) ashless dispersants -3: number average that the Bisuimi <br/> de polybutenyl group-containing succinic acid and tetraethylene pentamine molecular weight 1300 modified with boric acid (Mn = 1800) Viscosity index improvers: ethylene and propylene The graft copolymer obtained by graft-polymerizing methacrylate into the above copolymer, and the weight average molecular weight of 150,000 are suitable for the diesel engine equipped with DPF which is being studied as a future exhaust gas regulation countermeasure technology. A low phosphorus low ash type engine oil composition of the present invention. Each of these oils has practical performance equivalent to that of a conventional high phosphorus, high ash type engine oil (see Comparative Example 6 in Table 2). Then, by simply reducing the phosphorus content and the ash content, it is not possible to obtain engine oil having practical performance. This fact will be described below by comparing Tables 1 and 2. That is, the composition of Comparative Example 1
The amount of zinc di2-ethylhexyldithiophosphate added to the composition of Example 3 was 0.03% by mass in terms of phosphorus concentration.
Although the composition has been reduced to 10%, valve composition wear (damage to the camshaft) occurs in this composition, and oil deterioration (increase in acid value) of the composition itself is large. The composition of Comparative Example 2 is the same as that of Example 1.
The amount of calcium carbonate overbased calcium salicylate added to the composition of 0.06 in terms of calcium concentration.
Although the composition is reduced to the mass%, this composition causes valve system wear (damage to the camshaft) and also reduces the cleanliness of the piston. And the residual base number of the composition after use is zero. The composition of Comparative Example 3 was obtained by reducing the amount of boric acid-modified succinimide (ashless dispersant-1) added to the composition of Example 3 to 0.036 mass% in terms of boron. With this composition, valve train wear (damage to the camshaft) occurs and the piston cleanliness deteriorates.
Burning of the piston underside is especially noticeable. And
The residual base number of the composition after use is 0.1. Comparative Example 4
Of the ashless dispersant of the composition of Example 1,
Although it was replaced with a bis-type succinimide that had not been modified with boric acid, valve train wear (damage to the camshaft) occurred with this composition. The cleanliness of the piston ring groove and ring land was improved, but the cleanliness of the piston underside was lowered. The composition of Comparative Example 5 was obtained by replacing the ashless dispersant in the composition of Example 1 with a boric acid-modified bis-type succinimide having a number average molecular weight of 1800. Valve system wear (damage to camshaft) occurred. In addition, the acid value of the composition itself is slightly increased. The composition of Comparative Example 6 is a standard oil having good cleanliness according to JASO M 336-90 standard.
DD1 oil (CD , SAE3), which is a typical high phosphorus and high ash type engine oil, which is set as (Good Oil)
0), and the compositions of Examples 1 to 6 have low phosphorous and low ash oils, but have performance as good as that of DD1 oil, as described above.

The low phosphorus, low ash type engine oil composition of the present invention has excellent performances such as cleanliness, thermal stability, antiwear property, and oxidation stability, and therefore is used as a lubricating oil for land and marine diesel engines. And is particularly useful as a lubricating oil for diesel engines equipped with DPF.
Further, the engine oil composition of the present invention can be preferably used as a lubricating oil for gasoline engines and gas engines using LPG, CNG and the like as fuel.

Continuation of front page (51) Int.Cl. ⁷ Identification code FI C10M 159: 24) C10N 10:04 C10N 10:04 20:04 20:04 30:00 Z 30:00 30:04 30:04 30:06 30:06 30:08 30:08 30:10 30:10 40:25 40:25 60:14 60:14 (72) Inventor Yuichi Takahashi 8 Chidoricho, Naka-ku, Yokohama-shi Central Research Institute of Nippon Oil Co., Ltd. (56) References JP-A-7-102273 (JP, A) JP-A-7-207290 (JP, A) JP-A-7-268379 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) C10M 163/00 C10M 133/16 C10M 133/56 C10M 137/10 C10M 139/00 C10M 149/02 C10M 155/04 C10M 159/20-159/24 C10M 167/00 C10N 10:04 C10N 20 : 04 C10N 30:00 C10N 30:04-30:10 C10N 40:25-40:28 C10N 60:14

Claims (2)

(57) [Claims] 1. A mineral oil and / or synthetic oil as a base oil, (1) 0.04 to 0.08 wt% of zinc dialkyldithiophosphate in Li emissions equivalent concentration, (2) total base number 150～200MgKOH / calcium calcium overbased calcium salicylate and / or calcium borate overbased calcium salicylate having a total base number of 150 to 250 mg KOH / g.
0.07 to 0.22% by weight calcium equivalent concentration, and (3) a number average molecular weight of 2000 to 5000 Vista
Imide boric acid-modified succinic ashless dispersant type containing respectively 0.04 to 0.08% by weight boric oxygen concentration terms,
A diesel engine oil composition having a sulfated ash content of 0.4 to 0.8% by mass. Wherein the mineral oil and / or synthetic oil as a base oil, (1) 0.04 to 0.08 wt% of zinc dialkyldithiophosphate in Li emissions equivalent concentration, (2) total base number 150～200MgKOH / calcium calcium overbased calcium salicylate and / or calcium borate overbased calcium salicylate having a total base number of 150 to 250 mg KOH / g.
Calcium 0.05 to 0.2 wt% in concentration terms, and (3) total base number is 50～100MgKOH / g basic calcium phenate is and / or total base number is 1
0~50mgKOH / g 0.01~0.02% by weight of basic calcium sulfonate with calcium equivalent concentration is, and (4) a number average molecular weight of 2000 to 5000 Vista
Imide boric acid-modified succinic ashless dispersant type containing respectively 0.04 to 0.08% by weight boric oxygen concentration terms,
A diesel engine oil composition having a sulfated ash content of 0.4 to 0.8% by mass.